Relay



Patented Aug. 9, 1932 UNITED STATES PATENT OFFICE RAYMOND T. PIERCE, OF MILLBURN, NEW JERSEY, ASSIGNOR 'I'O WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION 01 PENNSYLVANIA RELAY Application filed. December 7, 1928. Serial No. 324,424.

My invention relates to circuit-protective devices and, more particularly, to an improved relay for effecting the disconnection of a circuit to be protected upon the occurrence of a predetermined electrical condition.

In relay devices of the prior art, and particularly in the case of relays of the induction type, it has been a common expedient to provide a plurality of taps for the energizing winding of the relay whereby the responsiveness of the relay may be controlled. In other Words, the magnitude of current required to cause the operation of the relay was predetermined by selecting the appropriate tap on the energizing winding thereof.

Further, in relays of the prior art, it has been customary, in order to impart definitetime characteristics to the relay operation, to insert a small transformer in the relay circuit having a core which is saturable at a point below the ordinary operating range of the instrument.

An object of the present invention, therefore, is to provide, in combination with a protective relay, an improved means for predetermining the responsiveness thereof and for imparting definite-time characteristics into the operation of the relay, which is relatively simple and accurate, as compared with the means heretofore employed.

In practicing my invention, I provide a variable-ratio transformer connected in the energizing circuit of an overload relay of the induction type. The transformer embodies a portion which is magnetically saturable, preferably at a flux magnitude below the normal operating range of the relay.

The single figure of the drawing is a diagrammatic view of a protective circuit embodying my invention.

Referring more particularly to the drawing, and induction relay 1 of the overload type is provided, having a main energizing winding 2 adapted to cooperate with auxiliary windings 3 to efiect the rotation of a disc armature 4 in a well known manner. Contacts 5 are controlled by the rotation of the disc to close a circuit in order to actuate a circuit interrupter for controlling the connection of the circuit 6 which is to be protected, in accordance with the usual practice.

It has been usual, in relays of this type in the prior art, to provide a plurality of taps on the winding 2 of the relay to predetermine the minimum value of current required to cause the operation of the relay. In the present invention, a variable-ratio transformer or regulator 7 is provided for accomplishing this function in a more simple and accurate maner.

The regulator 7 comprises a stationary core 8 having diametrically opposite pole portions which are provided with windings 9 for effecting the energization of the core.

As indicated in the drawing, the windings 9 are connected in series-circuit relation with a current transformer 10 of a usual type assowindings 9 will control the transformation ratio between these windings and, hence, will control the magnitude of the current traversing the conductors 13 and 14 and the relay winding 2.

A pointer 15, is rigidly mounted upon the rotatable core 11 to cooperate with a scale 16 mounted, in the present embodiment, upon the stationary core 8 to indicate the angular position of the rotatable armature.

i The pointer 15 and core 11 are adapted to be adjustably positioned with respect to the scale 16 by means of a non-magnetic arcuate plate member 18 secured to the core 8 and suitable set-screw means 17. It is obvious that any means may be employed for holding the pointer 15 and core 11 in any predetermined position, and the means illustrated in the drawing is to be understood as generic in character.

In order to impart definite-time characteristics to the operation of the relay, the cross-section area of the core 8 is made relatively small so that magnetic saturation occurs when the magnitude of the current traversing' the windings 9 attains a predetermined value. Preferably, this magnitude is below the normal operating range of current required for the operation of the relay.

In operation, assuming that it is desired to interrupt the circuit 6 When the current therein attains a magnitude of 4 amperes, the indicator 15 and the armature 11 are moved to the position indicated in the drawing. Since the current traversing the conductors 13 and 14 will be proportional to the current induced in the series transformer 10 and, hence, the current traversing the circuit 6, the relay will be operated when the current traversing the circuit 6 attains the desired magnitude. Upon operation of the relay, the contact means 5 thereof will close, after a certain predetermined time, depending upon the time setting of the relay, and operate a circuit interrupter to break the circuit 6.

Further, assuming that it is desired to interrupt the circuit 6 when the magnitude of the current therein is of a higher value, for example, 6 amperes, the indicator 15 and the rotatable armature 11 secured thereto may be moved to a position where the indicator 15 is on the graduation 6 of the scale 16. It will be obvious that, in this position of the armature 11, the magnitude of the current traversing the conductors 13 and 14 will be less than in the previously assumed condition, and the relay 2, therefore, will not be sufiiciently energized to cause the operation thereof until the current traversing the windings 9 of the regulator attains a magnitude proportional to a current of 6 amperes in the circuit 6.

Since the degree of energization of the winding 12 on the rotatable armature 11 may be varied from a maximum value, when the armature 11 is in the position shown, to a minimum value when the armature winding 12 is substantially at right angles to the position shown, the current responsiveness of the relay may be accurately predetermined over a Wide range and by relatively small more ments.

By my invention, I have provided means for varying the current responsiveness of an induction-type relay without resorting to the provision of taps on the energizing winding thereof, and I have imparted definite-time characterlstics to the operation of the relay without resorting to the provision of a separate saturable transformer in the relay circuit.

In accordance with my invention, the protective system disclosed is more accurate than systems heretofore known or employed and is simple in construction, as compared with previous devices for accomplishing similar results.

Various modifications may be made in my invention without departing from the s irit and scope thereof, and I desire, there 'ore, that only such limitations shall be placed thereon as are imposed by the prior art and are set forth in the appended claims.

. I claim as my invention:

1. The combination with an alternating current circuit, a circuit-interrupter therefor,

and a relay for controlling said interrupter, of means for supplying energy to said relay from said circuit including a variable-ratio transformer having a stationary magnetic circuit designed to be saturated by a current of predetermined magnitude below the working current value for said relay, a movable winding variably-inductively associated with said stationary magnetic circuit for energizing said relay and predetermining the sensitivity thereof, and means for adjustably determining the position of said movable Winding.

2. The combination with an alternating current transmission circuit and a control relay therefor, of a variable-ratio transformer having a primary winding energized from said circuit and disposed on a stationary magnetizable core which is saturable at current magnitudes within the working range of the control relay, a movable secondary winding associated with said core for energizing said control relay by a current bearing a predetermined relation to the current traversing said transmission circuit, and means for adjustably determining the position of said secondary winding.

3. The combination with a variable source of current and a control circuit, of means for supplying current from said source to said control circuit, including a variable-ratio transformer having a stationary saturable core, a primary winding thereon energized from said variable source, a secondary winding and means for adjustably mounting said secondary Winding to any of a plurality of predetermined inductively-related positions with respect to said primary winding for predetermining the degree of energization of mounting said secondary Winding to assume any of a plurality of positions to thereby vary the mutual inductance of said windings, and a relay responsive to the current in said secondary winding.

5. In a protective system, an alternating current circuit, a circuit interrupter therefor, a variable-ratio transforming device comprising a primary winding, a secondary Winding, a magnetic structure inductively connecting said windings and designed to be saturated in response to a current of predetermined value in said primary winding, and means for adjustably determining the relative positions of said windings to thereby determine their mutual inductance, means for energizing said primary winding in accordance with an electrical condition of said circuit, and a relay responsive to the current in said secondary winding for operating said interrupter.

6. In a protective system, an alternatingcurrent circuit, a circuit interrupter therefor, a variable-ratio transforming device comprising a pair of windings, a magnetic structure inductively connecting said windings and designed to saturate in response to a current of predetermined value in one of said windings, and means for adjustably determining the relative positions of said windings to thereby determine their mutual inductance, a relay for operating said interrupter, and energy-transference means connecting said circuit and said relay through said transforming device.

7. In a protective system, an alternatingcurrent, a circuit interrupter therefor, a variable-ratio transforming device comprising a saturab-le magnetic element, a second magnetic element magnetically associated with said saturable element and movable relatively thereto, a winding mounted upon each of said elements in inductive relation thereto, and means for adjustably determining the relative positions of said elements, a relay for operating said interrupter, and energy transference means connecting said circuit and said relay through said transforming device.

In testimony whereof, I have hereuntosubscribed my name this 23rd day of November,

RAYMOND T. PIERCE. 

